ConsumerFactory.java

/*******************************************************************************
 *
 * Copyright 2012-2015, the original author or authors.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obta a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *  
 *******************************************************************************/

package com.flipkart.aesop.eventconsumer;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Set;

import com.linkedin.databus.client.pub.DatabusCombinedConsumer;
import com.linkedin.databus.client.pub.DbusClusterConsumerFactory;
import com.linkedin.databus.client.pub.DbusClusterInfo;
import com.linkedin.databus.client.pub.DbusPartitionInfo;

/**
 * Class responsible for generating {@link List} of new instances of {@link AbstractEventConsumer} each it is called for
 * a particular partition.
 * @author Prakhar Jain
 */
public class ConsumerFactory implements DbusClusterConsumerFactory
{
	
	/**
	 * {@link List} of {@link AbstractEventConsumer} that is generated by
	 * {@link #createPartitionedConsumers(DbusClusterInfo, DbusPartitionInfo)}. For every call, new instances of Event
	 * Consumer has to be created.
	 */
	List<? extends EventConsumerFactoryBean<? extends AbstractEventConsumer>> eventConsumerFactoryList;

	/**
	 * Total Destination groups. Optional. If not set, it is calculated using the group Id set that is defined for each
	 * of the consumers generated by {@link #createPartitionedConsumers(DbusClusterInfo, DbusPartitionInfo)}.
	 */
	Integer totalDestinationGroups;

	public Collection<DatabusCombinedConsumer> createPartitionedConsumers(DbusClusterInfo clusterInfo,
	        DbusPartitionInfo partitionInfo)
	{
		List<AbstractEventConsumer> consumerList = new ArrayList<AbstractEventConsumer>();

		for (EventConsumerFactoryBean<? extends AbstractEventConsumer> eventConsumerFactory : eventConsumerFactoryList)
		{
			AbstractEventConsumer eventConsumer = eventConsumerFactory.getObject();
			consumerList.add(eventConsumer);
		}

		int maxGroupSpecified = 1;

		if (totalDestinationGroups == null)
		{
			for (AbstractEventConsumer eventConsumer : consumerList)
			{
				maxGroupSpecified = Math.max(maxGroupSpecified, getMaxGroupNo(eventConsumer.getDestinationGroupSet()));
			}

			totalDestinationGroups = maxGroupSpecified;
		}

		for (AbstractEventConsumer eventConsumer : consumerList)
		{
			eventConsumer.setTotalDestinationGroups(totalDestinationGroups);
		}

		return new ArrayList<DatabusCombinedConsumer>(consumerList);
	}

	/**
	 * Get max Group Id for
	 * @param destinationGroupSet
	 * @return Max Group No
	 */
	private int getMaxGroupNo(Set<Integer> destinationGroupSet)
	{
		int maxDestinationGroupNo = 0;

		for (Integer destinationGroupNo : destinationGroupSet)
		{
			maxDestinationGroupNo = Math.max(maxDestinationGroupNo, destinationGroupNo);
		}
		return maxDestinationGroupNo;
	}

	/**
	 * Sets the Event Consumer Factory List to be used for creating Event Consumer.
	 * @param eventConsumerFactoryList
	 */
	public void setEventConsumerFactoryList(
	        List<? extends EventConsumerFactoryBean<? extends AbstractEventConsumer>> eventConsumerFactoryList)
	{
		this.eventConsumerFactoryList = eventConsumerFactoryList;
	}

	/**
	 * Sets the total number of destination groups.
	 * @param totalDestinationGroups
	 */
	public void setTotalDestinationGroups(Integer totalDestinationGroups)
	{
		this.totalDestinationGroups = totalDestinationGroups;
	}
}